Global NEST Journal

The aim of this study was to optimize the removal of Naproxen (NPX) by the UV/ZnO photocatalytic process using response surface methodology based on Central Composite Design (CCD). The effect of parameters such as ZnO concentration, contact time, pH, temperature, and initial NPX concentration were studied. The ANOVA results indicated high coefficient values of adjusted R2 (0.9843) and predicted R2 (0.9695). The quadratic model with the highest R-squared designation was chosen to predict the NPX removal efficiency of the UV/ZnO process. Under optimal conditions that include an optimum initial NPX concentration of 21.59 mg/L, ZnO concentration of 371.15 mg/L, contact time of 73.92 min, pH of 6.87, and temperature of 24.35°C, a NPX removal efficiency value of 71.19% was obtained. The results show that the removal of NPX is most affected by the variables- initial NPX concentration, time, pH, and ZnO concentration, respectively, but temperature as a variable does not have a significant effect on the efficiency of the process. Moreover, the NPX photodegradation kinetics can be explained through the pseudo-first-order model. The UV/ZnO photocatalytic method has high potential for the removal of NPX, and that CCD is an appropriate method to optimize the operating conditions for NPX photodegradation.

Untreated wastewater can have important effects on the environment and human. The aim of the work was to evaluate the effectiveness of modified barley straw to remove malachite green from industrial wastewater. Studied variables were pH, contact time, initial malachite green concentration, and adsorbent dosage. Box–Behnken design method was used for modeling the process of adsorption. The results of analysis of variance showed that there are the significance relative among process parameters. The high value of R2 (0.9753) indicated that there was a high correlation between the predicted and experimental values. Removal efficiency of malachite green increased by increasing of modified barley straw dosage, pH and contact time, and decreasing of color concentration. Remove the color was better in alkaline conditions and the best pH was equal to 9.5. The optimum contact time to remove was 120 min. The findings of this study showed that Box-Behnken model can efficiently optimize the malachite green adsorption onto modified barley straw from aqueous solutions.

The long start-up time and high demand of anaerobic ammonium oxidation (anammox) limit the practical applications of the anammox process. In this study, granular sludge supported on activated carbon (AC) was used as seed sludge. The start-up time of the reactor was substantially shortened, and the expanded granular sludge bed (EGSB) reactor could be started quickly (in only 17 days). The nitrogen load rate (NLR) increased from 0.61 kg m-3 d-1 to 1.19 kg m-3 d-1, the removal rate of total nitrogen (TN) increased from 78.04% to83.15%, and the final ratio NH4+: NO2-: NO3- was 1:1.33:0.30. Moreover, in the gas analysis phase, the reactor load could be further improved and increased to 1.70 kg m-3 d-1 from the 18th–22nd day, and the reactor run stably. During this period, N2O and CO2 production was 0.8% and 0.02%, respectively. According to the analysis of microorganisms, the main functional microorganism in the reactor was Candidatus Kuenenia. The content of Candidatus Kuenenia increased by 5.45% after the reactor was started successfully. The color of sludge was brick red. This showed that the operation mode and inoculated sludge employed in this study are highly effective for the fast start-up of an EGSB reactor.

In this work, the aryldiazonium salts radical addition method has been used successfully to anchor 8-hydroxyquinoline (8-HQ) moieties onto the surface of Amberlite XAD-4 beads. The nitroaniline aryldiazonium salt was generated (in-situ) and covalently grafted onto Amberlite XAD-4 by aid of hypophosphorous acid as a catalyst to facilitate the anchorage of 8-HQ chelator making use of the conventional diazo coupling. The successfulness of the synthesized chelating resin was confirmed by (ATR-IR), (TGA) and (XPS). The risen was packed into cartridges and used with standard solid phase extraction (SPE) apparatus for the extraction of trace metals; Co (II), Ni (II) and Cu (II) from groundwater samples prior to their measurement by (ICP-MS). The resin exhibited more than 90% enhancement in capacity exchange relative to the plain Amberlite XAD-4. Under the optimum conditions the sorption capacity of the sorbent was 0.366, 0.265 and 0.328 (mM/g) for Co (II), Ni (II) and Cu (II) respectively. The sorbent showed efficient performance when applied for SPE of trace metals from groundwater real samples from AlMadinah AlMumnawarah, Saudi Arabia.